Methods, devices, and systems relating to a sensing device

ABSTRACT

Methods, devices, and systems relating to a sensing device are disclosed. A device may comprise a structure including a first surface and a second, opposite surface, wherein the structure comprises one or more segments. Further, the device may include a plurality of sensors disposed on the structure, wherein each segment of the one or more segments comprises a first sensor of the plurality of sensors coupled to the first surface and an associated second sensor of the plurality of sensors coupled to the second surface. Moreover, each sensor of the plurality of sensors may be configured to measure a strain exhibited on an adjacent surface of the structure at an associated segment of the one or more segments.

GOVERNMENT RIGHTS

The United States Government has certain rights in this inventionpursuant to Contract Nos. NAS8-97238 and NNMO7AA75C between the NationalAeronautics and Space Administration and Alliant Techsystems Inc.

TECHNICAL FIELD

This invention, in various embodiments, relates generally to measuringone or more characteristics of an object and, more specifically, tomethods, devices, and systems for determining a shape an object.

BACKGROUND

Reusable solid rocket motor (RSRM) designs can be found in many rocketryapplications, with perhaps the best known applications involving solidrocket boosters of the Space Shuttle, or the Ares 1 rocket. The solidrocket boosters of a spacecraft may be attached to opposite sides of amain external tank of the spacecraft and, together, may furnish themajority of the thrust required to launch the spacecraft from its mobilelaunch platform and contribute to accelerate the vehicle to more thanabout 4800 km per hour (3,000 miles per hour) before detaching andseparating from the external tank.

FIG. 1 is a perspective view of an example of a conventional RSRM 100 ofa spacecraft vehicle. RSRM 100 comprises a plurality of detachablesegments connected to each other by field joints 120 and factory joints140. The term “field joint” is commonly used in the field of rocketry todenote joints capable of being assembled in either a factory or thefield. Field joints 120 and segmented design provides maximumflexibility in transportation, handling, recovery, refurbishment,assembly, and fabrication of RSRM 100. For example, the segmenting ofthe solid rocket motor facilitates propellant casting procedures andpermits transportation of the large segments on heavy-duty railcarsincapable of carrying an assembled RSRM 100.

FIG. 2A is a partially cut-away view of a conventional RSRM comprisingfield joints having a pressure-actuated joint system. With reference toFIG. 2A, RSRM 100 comprises a forward segment 121, a forward-centersegment 122, an aft-center segment 124, and an aft segment 126. Segments121, 122, 124, and 126 may collectively contain a solid propellant grainstructure, which is illustrated as a center-perforated propellant grainstructure 140. More specifically, each of segments 121, 122, 124, and126 houses a portion or segment of propellant grain structure 140.

FIG. 2B is a sectional view of one of the field joints shown in FIG. 2A,and in particular is a sectional view of a forward field joint 112connecting a forward segment 121 and forward-center segment 122 of theRSRM 100 of FIG. 2A. FIG. 2C is a sectional view of another one of thefield joints shown in FIG. 2A, and in particular is a sectional view ofa center field joint 112 a connecting the forward-center segment 122 andan aft-center segment 124 of the RSRM 100 of FIG. 2A. FIG. 2D is asectional view of still another one of the field joints shown in FIG.2A, and in particular is a sectional view of an aft field joint 112 bconnecting the aft-center segment 124 and the aft segment 126 of theRSRM 100 of FIG. 2A. FIG. 2E is a zoomed in, enlarged view of theforward field joint 112 of FIG. 2B.

Also illustrated in FIG. 2B are inhibitors 193 and 203, each of which isshaped as an annular radial disk. With reference to FIG. 2E, inhibitors193 and 203 are disposed on opposite sides of a channel 204, and may beapplied after partial propellant cure. Inhibitors 193 and 203 may beused to thermally protect propellant grain structure 140 and controlgrain ignition. Inhibitors 193 and 203 may, for example, may includematerials such as nitrile butadiene rubber (NBR) and carboxyl-terminatedpolybutadiene copolymer. Inhibitors 193 and 203 may also include otheringredients, for example, fillers such as asbestos. Inhibitors 193 and203 may be designed to bond to and cure simultaneously with propellantgrain structure 140.

As propellant grain structure 140 burns, portions of inhibitors 193 and203 that remain within an aperture of RSRM 100 may cause RSRM 100 toexperience undesired oscillations. More specifically, as an example,vortex shedding from inhibitor 193 or inhibitor 203 may result inoscillations in the combustion chamber of RSRM 100 that may undesirablyshake an associated orbiter. Conventionally, in an effort to betterunderstand oscillations caused by an inhibitor within a combustionchamber of a rocket motor, real-time radiography has been utilized tomonitor a shape and a position of the inhibitor. However, real-timeradiography has proven to be inadequate due to slow frame rate and poorresolution.

The inventors have appreciated that there is a need for enhancedmethods, systems, and devices for measuring characteristics of an objectand, in particular, for methods, devices, and systems for determining ashape of an object.

BRIEF SUMMARY OF THE INVENTION

An embodiment of the present invention comprises a method of determiningat least one characteristic of at least a portion of an object. Themethod may comprise at least substantially aligning at least a portionof a sensing device including a structure having a plurality of sensorscoupled thereto with at least a portion of an object. The structure maycomprise one or more segments and each segment includes a first sensorof the plurality of sensors coupled to a first surface and a secondsensor of the plurality of sensors coupled to a second, oppositesurface. The method may further include sensing a strain with each ofthe first sensor and the second sensor at each segment of the one ormore segments. Furthermore, the method may include determining acurvature of each segment of the one or more segments and determining atleast one of a shape and a position of the at least a portion of theobject from the determined curvature of each segment.

Another embodiment of the present invention comprises a method ofdetermining a shape of an inhibitor within a rocket motor. The methodmay include positioning a sensing device comprising a plurality ofstrain gauges adjacent to and at least in substantial alignment with aninhibitor in a rocket motor. In addition, the method may includedetermining a shape of the inhibitor by determining a shape of thesensing device.

Another embodiment of the present invention comprises a method ofdetermining a shape of at least a portion of an inhibitor within arocket motor. The method comprises sensing a strain exhibited on each ofa first surface and a second, opposite surface of each segment of one ormore segments of a structure embedded within at least a portion of aninhibitor within a rocket motor. Additionally, the method may comprisedetermining a curvature of each segment of the one or more segments froman associated strain sensed on each of the first surface and the secondsurface. Moreover, the method may include determining a shape of the atleast a portion of the inhibitor from the determined curvature of eachsegment of the structure.

Another embodiment of the present invention comprises a device. Thedevice may comprise a structure including a first surface and a second,opposite surface, wherein the structure comprises one or more segments.Further, the device may include a plurality of sensors disposed on thestructure, wherein each segment of the one or more segments comprises afirst sensor of the plurality of sensors coupled to the first surfaceand an associated second sensor of the plurality of sensors coupled tothe second surface. Moreover, each sensor of the plurality of sensorsmay be configured to measure a strain exhibited on an adjacent surfaceof the structure at an associated segment of the one or more segments.

Another embodiment of the present invention comprises a system. Thesystem may comprise a device comprising a structure including a firstside and a second side, opposite the first side, wherein the structurecomprises a plurality of segments. The device may further include aplurality of sensors disposed on the structure, wherein each segmentcomprises a sensor on each of the first side and the second side.Moreover, each sensor of the plurality of sensors is configured tomeasure a strain exhibited on an adjacent surface of the structure at anassociated segment of the one or more segments. The system may furthercomprise a computer operably coupled to the device and configured toreceive data from each sensor of the plurality of sensors.

Yet another embodiment of the present invention includes a rocket motor.The rocket motor comprises one or more inhibitors, wherein at least oneinhibitor of the one or more inhibitors includes a sensing deviceembedded therein. The sensing device may comprise a structure includingone or more sensors disposed on a first surface, wherein each sensor ofthe one or more sensors disposed on the first surface is associated witha sensor of one or more sensors disposed on a second surface, oppositethe first surface. Further, each sensor of the one or more of sensors isconfigured to measure a strain exhibited on an adjacent surface of thestructure.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is perspective view of an example of a conventional reusablesolid rocket motor of a spacecraft vehicle;

FIG. 2A is a partially cut-away view of a conventional reusable solidrocket motor comprising field joints having a pressure-actuated jointsystem;

FIG. 2B is a sectional view of one of the field joints shown in FIG. 2A,and in particular is a sectional view of a forward field jointconnecting a forward segment and a forward-center segments of the solidrocket motor of FIG. 2A;

FIG. 2C is a sectional view of another one of the field joints shown inFIG. 2A, and in particular is a sectional view of a center field jointconnecting a forward-center segment and an aft-center segment of thesolid rocket motor of FIG. 2A;

FIG. 2D is a sectional view of still another one of the field jointsshown in FIG. 2A, and in particular is a sectional view of an aft fieldjoint connecting an aft-center segment and an aft segment of the solidrocket motor of FIG. 2A;

FIG. 2E is a zoomed in, enlarged view of the forward field joint of FIG.2B;

FIG. 3 illustrates a “half-bridge” Wheatstone bridge circuit;

FIG. 4 illustrates a structure comprising a plurality of segments havinga plurality of sensors coupled thereto, in accordance with an embodimentof the present invention;

FIG. 5 is another depiction of the structure of FIG. 4 comprising aplurality of segments having a plurality of sensors coupled thereto;

FIG. 6 illustrates a plurality of sensors integrated within a flexcircuit, according to an embodiment of the present invention;

FIG. 7 illustrates a system including a computer operably coupled to asensing device, in accordance with an embodiment of the presentinvention;

FIG. 8 is a cross-sectional view of a portion of a rocket motor having asensing device embedded within an inhibitor, according to an embodimentof the present invention;

FIG. 9 is an enlarged cross-sectional view of a portion of the rocketmotor of FIG. 8;

FIG. 10 is a perspective cut-away view of a portion of a rocket motorhaving a sensing device positioned within an inhibitor, in accordancewith an embodiment of the present invention;

FIG. 11 illustrates a top-down view of the inhibitor of FIG. 10 with asensing device positioned therein, according to an embodiment of thepresent invention;

FIG. 12 is a cross-sectional view of a portion of the rocket motor ofFIG. 10 having a sensing device positioned within an inhibitor,according to an embodiment of the present invention;

FIG. 13 is another illustration of a portion of a rocket motor having asensing device positioned within an inhibitor adjacent a propellant, inaccordance with an embodiment of the present invention;

FIG. 14 illustrates a sensing device coupled to a game controller,according to an embodiment of the present invention; and

FIG. 15 illustrates a sensing device positioned adjacent to and at leastin substantial alignment with a surface of an object, in accordance withan embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, circuits and functions may be shown inblock diagram form in order not to obscure the present invention inunnecessary detail. Conversely, specific circuit implementations shownand described are examples only and should not be construed as the onlyway to implement the present invention unless specified otherwiseherein. Additionally, block definitions and partitioning of logicbetween various blocks is exemplary of a specific implementation. Itwill be readily apparent to one of ordinary skill in the art that thepresent invention may be practiced by numerous other partitioningsolutions. For the most part, details concerning timing considerationsand the like have been omitted where such details are not necessary toobtain a complete understanding of the present invention and are withinthe abilities of persons of ordinary skill in the relevant art.

It should be understood that any reference to an element herein using adesignation such as “first,” “second,” and so forth does not limit thequantity or order of those elements, unless such limitation isexplicitly stated. Rather, these designations may be used herein as aconvenient method of distinguishing between two or more elements orinstances of an element. Thus, a reference to first and second elementsdoes not mean that only two elements may be employed there or that thefirst element must precede the second element in some manner. Also,unless stated otherwise, a set of elements may comprise one or moreelements.

In this description, some drawings may illustrate signals as a singlesignal for clarity of presentation and description. It will beunderstood by a person of ordinary skill in the art that the signal mayrepresent a bus of signals, wherein the bus may have a variety of bitwidths and the present invention may be implemented on any number ofdata signals, including a single data signal. In describing embodimentsof the present invention, the systems and elements incorporatingembodiments of the invention are described to facilitate an enhancedunderstanding of the function of the described embodiments of theinvention as it may be implemented within these systems and elements.

When executed as firmware or software, the instructions for performingthe methods and processes described herein may be stored on a computerreadable medium. A computer readable medium includes, but is not limitedto, magnetic and optical storage devices such as disk drives, magnetictape, CDs (compact disks), DVDs (digital versatile discs or digitalvideo discs), and semiconductor devices such as RAM, DRAM, ROM, EPROM,and Flash memory.

A strain gauge is a strain-sensitive device employed to sense strain,such as that caused by stress in the form of tensile or compressiveforces applied to a structure. Conventional strain gauges typicallyemploy a strain sensing element adhered to at least one surface on orwithin the structure such that, when the structure exhibits a strain inresponse to an applied stress, the resistance of the sensing elementchanges in proportion to the sensed strain. The measured strain isgenerally calculated based on the change in resistance in the sensingelement as the structure is compressed or elongated, thus exhibiting ormanifesting the strain. Strain gauges can be used to measure bending,axial and torsional strain, or a combination of strain effects, on astructure resulting from various applied loads.

Strain gauges may include foil type strain gauges comprising a patternof resistive foil mounted on a backing surface. Furthermore, straingauges may include semiconductor strain gauges which are often preferredover foil gauges when measuring small amounts of strain. Strain gaugesmay be attached to a flexible plastic substrate which, in turn, iscoupled (e.g., bonded) to the structure for which the strain is to bedetermined. As known by one having ordinary skill in the art, in orderto measure a physical property with one or more coupled sensors, thesensors may be integrated within a measurement circuit configured tomeasure the changes in an electrical property corresponding to a changein a physical property, such as temperature or strain. For example, astrain gauge may be implemented within a Wheatstone bridge circuit,which converts the sensed resistance to a voltage signal. To obtain thevoltage signal, it is generally required to further connect adifferential amplifier and a current source to the Wheatstone bridgecircuit. As a more specific example, a measurement circuit may include a“half-bridge” Wheatstone bridge circuit including at least two sensorsconfigured to measure strain.

FIG. 3 illustrates an example of a “half-bridge” Wheatstone bridgecircuit 250. Wheatstone bridge circuit includes branches 310A, 310B,310C, and 310D. First branch 310A includes a first sensor 304A, secondbranch 310B includes a second sensor 304B, and third branch 310C andfourth branch 310D may include resistors R₁ and R₂, respectively. Forexample only, and not by way of limitation, each of first sensor 304Aand second sensor 304B may comprise a strain gauge. Operation of a“half-bridge” Wheatstone bridge is well known in the art and, therefore,will not be discussed in detail. It is noted, however, that Wheatstonebridge circuit 250 may be configured such that a strain associated withfirst sensor 304A and a strain associated with second sensor 304B may besimultaneously measured.

FIG. 4 illustrates a structure 300 comprising a plurality of segments302A-302E having a plurality of sensors 304A coupled thereto, inaccordance with an embodiment of the present invention. FIG. 5 isanother depiction of a portion of the structure 300 of FIG. 4 comprisinga plurality of segments 302A, 302B having a plurality of sensors coupledthereto. Referring to FIGS. 4 and 5 the structure 300 may include aplurality of segments 302 (i.e., segments 302A-302E in FIG. 4 andsegment 302A and 302B in FIG. 5), wherein each segment 302 comprises apair of sensors 304A, 304B associated therewith (e.g., being bondedthereto). More specifically, each of the plurality of segments 302comprises a first sensor 304A coupled to a first surface 306 and asecond sensor 304B coupled to a second surface 308 of the structure 300,wherein the second surface 308 is opposite the first surface 306. It isnoted that neither second surface 308 nor second sensor 304B are visiblein the perspective view in FIG. 4; however, second surface 308 andsecond sensor 304B are visible in the depiction of structure 300 in FIG.5. The sensors 304A, 30B may comprise a strain gauge. By way of exampleonly, the structure 300 may comprise a flexible metal strip having athickness D of approximately 0.7 inch. Although FIGS. 4 and 5 illustratestructure 300 including five segments and two segments, respectively,the present invention is not so limited and structure 300 may compriseany number of segments.

With continued reference to FIGS. 4 and 5, as will be understood by aperson having ordinary skill in the art, as a segment (e.g., segment302A) of structure 300 bends, sensor 304A and associated sensor 304B(see FIG. 5) may each measure a strain. More specifically, as anexample, as segment 302A bends in one direction, sensor 304A may bestretched and a strain measured by sensor 304A may be determined.Furthermore, sensor 304B (see FIG. 5) may be compressed and a strainmeasured by sensor 304B may also be determined. After an amount ofstrain measured by each of sensor 304A and sensor 304B is determined, acurvature of an associated segment (e.g., segment 302A) at a moment intime may be determined according to methods known in the art. Forexample only, a curvature of associated segment 302A may be determinedaccording to well known beam deflection theory. Furthermore, thecurvature of segment 302A may be integrated over a length L of segment302A to determine a shape of segment 302A at a moment in time. Moreover,after determining a shape of every other segment 302 (i.e., segments302B-302E) of structure 300 in a similar manner, a shape of structure300 at a moment in time may be determined. Furthermore, a method fordetermining a shape of structure 300 at a moment in time may be repeatedat a specific frequency to determine a shape of structure 300 as afunction of time. Moreover, the shape of structure 300 may be used todetermine a position of structure 300 relative to a known originalposition and original shape of structure 300.

FIG. 6 illustrates a plurality of sensors 304A, 304B integrated within aflex circuit 390 according to an embodiment of the present invention. Inother words, according to one embodiment illustrated in FIG. 6, sensors304A, 304B and associated circuitry (e.g., Wheatstone bridges) may beintegrated within a flex circuit 390, as will be understood by a personhaving ordinary skill in the art. In this embodiment, flex circuit 390may be folded along a center line 392 and wrapped around and coupled toa structure 300.

FIG. 7 illustrates a system 660 including a computer 662 operablycoupled to sensing device 650 in accordance with an embodiment of thepresent invention. The sensing device 650 may include structure 300,sensors 304A, 304B, and associated circuitry, the examples of which aredescribed with reference to FIGS. 3-5. The sensing device 650 may bepositioned adjacent to and at least in substantial alignment with anobject 664 for which a shape is to be determined. As described below,object 664 may comprise, for example only, an inhibitor within a rocketmotor, a body part (e.g., a limb), a video game input device, orconstruction material (e.g., a piece of wood). It is noted that,depending on the application, sensing device 650 may be associated withobject 664, including being positioned adjacent object 664, coupled toobject 664, bonded to object 664, embedded within object 664, or anycombination thereof. Computer 662 may include a processor 666 and amemory 668. Memory 668 may include a computer readable medium (e.g.,data storage device 670), which may include, but is not limited to,magnetic and optical storage devices such as disk drives, magnetic tape,CDs (compact disks), DVDs (digital versatile discs or digital videodiscs), and semiconductor devices such as RAM, DRAM, ROM, EPROM, andFlash memory. Memory 668 may include one or more software applicationsconfigured for performing various methods described herein. For example,memory 668 may include one or more software applications (e.g.,instructions) configured for receiving data from sensing device 650 and,thereafter, computing one or more characteristics associated with object664. For example, a shape of object 664, a position of object 664, avibrational frequency of object 664, an erosion rate of object 664, andany harmonic frequencies associated with object 664 may each becomputed, as described more fully below. One or more characteristicsassociated with the object 664 may also be transferred to the computer662.

The devices, systems, and methods of the various embodiments describedherein have a multitude of different applications. As non-limitingexamples, the various embodiments of the present disclosure may beutilized within rocket motor applications, video gaming applications,construction applications, industrial process applications, and medicalapplications.

One non-limiting example application may comprise employing sensingdevice 650 to monitor one or more characteristics (e.g., a shape) of aninhibitor within a rocket motor (e.g., RSRM). FIG. 8 is across-sectional view of a portion of a rocket motor 600 according to anembodiment of the present invention. FIG. 9 is an enlargedcross-sectional view of a portion of the rocket motor 600 of FIG. 8.Referring to FIGS. 8 and 9 rocket motor 600 comprises a field joint 612connecting a first segment 621 and a second segment 622. For example,first segment 621 may comprise a forward segment and second segment 622may comprises a forward-center segment. Segments 621 and 622 maycollectively contain a solid propellant grain structure, which isillustrated as a center-perforated propellant grain structure 640. Morespecifically, each of segments 621 and 622 may house a portion orsegment of propellant grain structure 640. Also illustrated are firstand second inhibitors 630, 632, each of which may be shaped as anannular radial disk. As will be understood by a person having ordinaryskill in the art, the first inhibitor 630 may comprise a forward-facingfield joint inhibitor. Furthermore, the first inhibitor 630 may comprisefor example, a polybenzimidazole fiber reinforced nitrile butadienerubber (PBI-NBR) inhibitor and second inhibitor 632 may comprise, forexample, a castable inhibitor. FIG. 9 is a zoomed in, enlargedcross-sectional view of a portion of field joint 612 and first andsecond inhibitors 630, 632.

As further illustrated in FIGS. 8 and 9, sensing device 650 may beembedded within first inhibitor 630. As will be understood by personhaving ordinary skill in the art, first inhibitor 630 may comprise aplurality of viscoelastic material sheets in a layered arrangement,wherein each material sheet may be comprised of one of asbestos fiberreinforced nitrile butadiene rubber (ASNBR) and PBI-NBR. Accordingly,before first inhibitor 630 is cured, sensing device 650 may bepositioned between adjacent material sheets of first inhibitor 630.Thereafter, a curing process (e.g., vulcanization) may be performed toembed sensing device 650 within first inhibitor 630. Sensing device 650may be positioned (e.g., centered) between a top surface of firstinhibitor 630 and a bottom surface of first inhibitor 630. Although notillustrated in FIG. 9, second inhibitor 632 may also include a sensingdevice embedded therein.

FIG. 10 illustrates a perspective cut-away view of a portion of a rocketmotor 700 including a sensing device 650 positioned within an inhibitor730, in accordance with an embodiment of the present invention. Therocket motor 700 includes a casing 702 and a propellant 704 with anaperture 706 extending therethrough. Portion of rocket motor 700 alsoincludes an inhibitor 730, which may comprise first inhibitor 630illustrated in FIGS. 8 and 9. Furthermore, sensing device 650, which isembedded within inhibitor 730, is also illustrated. FIG. 11 illustratesa top-down view of the inhibitor 730 of FIG. 10 with sensing device 650positioned therein, according to an embodiment of the present invention.FIG. 12 is a cross-sectional view of a portion of rocket motor 700 ofFIG. 10 having a sensing device 650 positioned within inhibitor 730,according to an embodiment of the present invention. As illustrated ineach of FIGS. 10-12, sensing device 650 may extend from an outer radialedge 656 of inhibitor 730 to an inner radial edge 658 of inhibitor 730.

FIG. 13 is another illustration of a portion of rocket motor 700including sensing a device 650 positioned within inhibitor 730 adjacenta propellant 704, in accordance with an embodiment of the presentinvention. It is noted that FIG. 13 illustrates portion of rocket motor700 after a portion of a propellant (e.g., propellant 704) has beendepleted (e.g., burned, consumed, etc.). Reference numeral 750illustrates an area (i.e., a void) that had previously comprisedpropellant 704. As a result of the propellant being depleted, a portionof inhibitor 730 adjacent area 750 may be unsupported. Therefore, aportion of inhibitor 730 adjacent area 750 may be displaced within anaperture of rocket motor 700 and may cause undesired oscillations withinrocket motor 700. More specifically, as an example, vortex shedding frominhibitor 730 may result in oscillations in the combustion chamber ofrocket motor 700 that may undesirably shake an associated orbiter. Aswill be understood by a person having ordinary skill in the art, a shapeand a position of sensing device 650 may be dependent on a shape and aposition of inhibitor 730. Stated another way, each of a shape and aposition of sensing device 650 may be similar, or identical, to that ofinhibitor 730. Accordingly, by measuring a shape of sensing device 650,a shape of inhibitor 730 may be determined. Furthermore, a relativeposition of inhibitor 730 may be determined by determining a relativeposition of sensing device 650.

As noted above with respect to FIGS. 4 and 5, a method for determining ashape of a structure may be repeated at a certain frequency to determinea shape of the structure as a function of time. With reference to FIG.13, by employing the methods described above, a shape of sensing device650 and, therefore, a shape of inhibitor 730 as a function of time maybe determined. Furthermore, according to methods known in the art, avibrational frequency of inhibitor 730 may be determined from the shapeof sensing device 650 as a function of time. As one example, avibrational frequency of inhibitor 730 may be mathematically determinedfrom the shape of sensing device 650 as a function of time and a knownmeasurement rate (i.e., the frequency at which measurements are taken).As another example, a vibrational frequency of inhibitor 730 may bedetermined by visually observing the shape of inhibitor 730 as afunction of time. Furthermore, for example, a Fourier transform may beperformed on the time-domain data (i.e., the shape of inhibitor 730 as afunction of time) to generate frequency spectra, which may be used todetermine a vibrational frequency and any harmonic frequenciesassociated with inhibitor 730 that may exist.

Furthermore, as a propellant (e.g., propellant 704) within a rocketmotor is depleted (e.g., burns), a portion of an inhibitor (e.g.,inhibitor 730) and adjacent portions of sensing device 650 may also burnand disintegrate. With reference to FIGS. 4, 5, and 13, as segment 302Aburns and possibly disintegrates, associated sensors 304A and 304B mayalso disintegrate and, therefore, may not produce accurate measurements,if any measurements at all. Accordingly, an erosion rate of inhibitor730 may be determined by monitoring a loss of measured data from sensingdevice 650. Stated another way, as a pair of associated sensors (i.e.,sensors 304A and 304B) within a segment (e.g., segment 302A) of sensingdevice fail to produce data, it may be assumed that the sensors and thesegment, as well as the portion of the inhibitor, which was previouslyadjacent to the sensors, has burned and disintegrated.

Various embodiments, as described above, may enable for one or morecharacteristics of an inhibitor within a combustion chamber of a rocketmotor to be monitored. Accordingly, it may be possible to betterunderstand why and how one or more characteristics of the inhibitoraffect, and possibly cause, oscillations within a rocket motor. Forexample, embodiments of the present invention may enable one todetermine if, and possibly how, a shape and/or the flexibility of aninhibitor affects oscillations within a rocket motor. With a betterunderstanding of a relationship between inhibitors and oscillationswithin a rocket motor, inhibitor designs may be modified in an effort tominimize the oscillations.

As noted above, the devices, systems, and methods of the variousembodiments described herein have a multitude of different applicationsin addition to the rocket motor applications described above. Onecontemplated application of embodiments of the present disclosure is invideo gaming. For example, sensing device 650 may be utilized todetermine a position and a direction of an input device (e.g., a gamecontroller) relative to a fixed reference.

For example, FIG. 14 illustrates a sensing device 650 coupled to a gamecontroller 782, according to an embodiment of the present invention. Afirst end 651 of sensing device 650 may be coupled to a stationaryreference 780, such as a video game console, and a second end 653 ofsensing device 650 may be coupled to a game controller 782 (e.g., asword). The position and orientation of game controller 782 may then bedetermined by integrating a measured curvature of sensing device 650from first end 651 of sensing device 650 to second end 653 of sensingdevice 650.

As another example, embodiments of the invention may be utilized withinmedical applications. FIG. 15 illustrates sensing device 650 positionedadjacent to and at least in substantial alignment with a surface 822 ofan object 830, in accordance with an embodiment of the presentinvention. In one example in which object comprises a limb (e.g., an armor a leg), sensing device 650 may be used to determine a range of motionof the limb. In another example in which object 820 comprises a chest ofa living being, sensing device 650 may be used to monitor breathingpatters by measuring a geometry of the chest over time. Othercontemplated examples may include utilizing sensing device 650 formeasuring muscle contractions or a curvature of a spine. Moreover,sensing device 650 may used to monitor characteristics (e.g., shape andposition) of a surgeon's hand while performing surgery.

In addition, embodiments of the present invention may be employed totransfer a contour of a real world object to a computer (e.g., computer662). For example, with reference again to FIG. 15, sensing device 650may be positioned on surface 822 of object 820 (e.g., a curved piece ofwood) in a manner so that a contour of sensing device 650 at leastsubstantially matches a contour of object 820. The shape of sensingdevice 650 and, thus, the contour of the object 820 may then betransferred to a computer. Similarly, sensing device 650 may be used totransfer a contour of a virtual object to a real world object. Forexample, sensing device 650 may be placed on a real world object (e.g.,a board or a piece of cloth) and positioned in a manner to match acontour of a virtual object displayed on a computer screen. It is notedthat the computer may include software configured to inform a user whena contour of sensing device 650 matches a contour of a virtual object.After tracing the contour of sensing device 650 onto the real worldobject, the real world object may be cut accordingly. As yet anotherexample, sensing device 650 may be used for angle measurements in theconstruction industry.

Specific embodiments have been shown by way of example in the drawingsand have been described in detail herein; however, the invention may besusceptible to various modifications and alternative forms. It should beunderstood that the invention is not intended to be limited to theparticular forms disclosed. Rather, the invention includes allmodifications, equivalents, and alternatives falling within the scope ofthe invention as defined by the following appended claims, and theirlegal equivalents.

1. A method of determining at least one characteristic of at least aportion of an object, comprising: at least substantially aligning atleast a portion of a sensing device including a structure having aplurality of sensors coupled thereto with at least a portion of anobject, wherein the structure comprises one or more segments and eachsegment includes a first sensor of the plurality of sensors coupled to afirst surface and a second sensor of the plurality of sensors coupled toa second, opposite surface; sensing a strain with each of the firstsensor and the second sensor at each segment of the one or moresegments; determining a curvature of each segment of the one or moresegments; and determining at least one of a shape and a position of theat least a portion of the object from the determined curvature of eachsegment.
 2. The method of claim 1, wherein at least substantiallyaligning a sensing device including a structure having a plurality ofsensors coupled thereto with at least a portion of an object comprisesembedding the sensing device within the at least a portion of theobject.
 3. The method of claim 2, wherein embedding the sensing devicewithin the at least a portion of the object comprises embedding thesensing device in an inhibitor within a rocket motor.
 4. The method ofclaim 1, wherein at least substantially aligning a sensing deviceincluding a structure having a plurality of sensors coupled thereto withat least a portion of an object comprises coupling the sensing device tothe at least a portion of the object.
 5. The method of claim 1, whereinat least substantially aligning a sensing device including a structurehaving a plurality of sensors coupled thereto with at least a portion ofan object comprises at least substantially aligning a sensing deviceincluding a structure having a plurality of strain gauges coupledthereto with the at least a portion of the object.
 6. The method ofclaim 1, wherein at least substantially aligning at least a portion of asensing device comprises coupling the portion of the sensing device to agame controller.
 7. The method of claim 6, further comprising couplinganother portion of the sensing device to a stationary reference.
 8. Themethod of claim 1, wherein determining at least one of a shape and aposition comprises determining a shape of the at least a portion of theobject and transferring the shape to a computer.
 9. The method of claim1, wherein at least substantially aligning at least a portion of asensing device including a structure having a plurality of sensorscoupled thereto with at least a portion of an object comprises at leastsubstantially aligning at least a portion of the sensing device with atleast a portion of one of a limb, a chest, a muscle, and a spine.
 10. Amethod of determining a shape of an inhibitor within a rocket motor,comprising: positioning a sensing device comprising a plurality ofstrain gauges adjacent to and at least in substantial alignment with aninhibitor in a rocket motor; and determining a shape of the inhibitor bydetermining a shape of the sensing device.
 11. The method of claim 10,wherein positioning a sensing device comprising a plurality of straingauges adjacent to and at least in substantial alignment with aninhibitor comprises embedding the sensing device in the inhibitor. 12.The method of claim 10, wherein determining a shape of the sensingdevice comprises determining a curvature of the sensing device.
 13. Themethod of claim 10, wherein determining the shape of the sensing deviceincludes measuring a strain exhibited on each of the plurality of straingauges.
 14. A method of determining a shape of at least a portion of aninhibitor within a rocket motor, comprising: sensing a strain exhibitedon each of a first surface and a second, opposite surface of eachsegment of one or more segments of a structure associated with at leasta portion of an inhibitor within a rocket motor; determining a curvatureof each segment of the one or more segments from an associated strainsensed on each of the first surface and the second surface; anddetermining a shape of the at least a portion of the inhibitor from thedetermined curvature of each segment of the structure.
 15. The method ofclaim 14, wherein determining a shape of the at least a portion of theinhibitor comprises determining a shape of the structure.
 16. The methodof claim 15, wherein determining a shape of the structure comprisesdetermining a shape of each segment of the one or more segments from thedetermined curvature of each segment.
 17. The method of claim 14,further comprising determining a shape of the at least a portion of theinhibitor as a function of time.
 18. The method of claim 17, furthercomprising generating frequency spectra from the shape of the at least aportion of the inhibitor as a function of time.
 19. The method of claim14, further comprising determining a vibrational frequency of the atleast a portion of the inhibitor.
 20. The method of claim 14, furthercomprising determining a position of the at least a portion of theinhibitor relative to an original position of the at least a portion ofthe inhibitor.
 21. The method of claim 14, further comprisingdetermining an erosion rate of the at least a portion of the inhibitor.22. A device, comprising: a structure including a first surface and asecond, opposite surface, wherein the structure comprises one or moresegments; and a plurality of sensors disposed on the structure, whereineach segment of the one or more segments comprises a first sensor of theplurality of sensors coupled to the first surface and an associatedsecond sensor of the plurality of sensors coupled to the second surface;wherein each sensor of the plurality of sensors is configured to measurea strain exhibited on an adjacent surface of the structure at anassociated segment of the one or more segments.
 23. The device of claim22, wherein each sensor of the plurality of sensor comprises a straingauge.
 24. The device of claim 22, wherein the structure comprises ametal strip having a thickness of approximately 0.7 inch.
 25. The deviceof claim 22, wherein the plurality of sensors are integrated within aflex circuit coupled to the structure.
 26. The device of claim 22,wherein the first sensor and the associated second sensor are integratedwithin a “half-bridge” Wheatstone bridge circuit.
 27. A system,comprising: a device, comprising: a structure including a first side anda second side, opposite the first side, wherein the structure comprisesa plurality of segments; and a plurality of sensors disposed on thestructure, wherein each segment comprises a sensor on each of the firstside and the second side; wherein each sensor of the plurality ofsensors is configured to measure a strain exhibited on an adjacentsurface of the structure at an associated segment of the one or moresegments; and a computer operably coupled to the device and configuredto receive data from each sensor of the plurality of sensors.
 28. Arocket motor, comprising: one or more inhibitors, wherein at least oneinhibitor of the one or more inhibitors includes a sensing devicepositioned therein, the sensing device comprising: a structure includingone or more sensors disposed on a first surface, wherein each sensor ofthe one or more sensors disposed on the first surface is associated witha sensor of one or more sensors disposed on a second surface, oppositethe first surface; wherein each sensor of the one or more of sensors isconfigured to measure a strain exhibited on an adjacent surface of thestructure.
 29. The rocket motor of claim 28, wherein the at least oneinhibitor comprises a forward-facing field joint inhibitor.